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Thread: Pure Tone Average and Audibility Index

  1. #1
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    Default Pure Tone Average and Audibility Index

    On my audiogram there is a PTA(pure tone average) and AI (audibility index) I've Googled to understand how they are calculated, but do they have any real use or predictive ability? I understand that the lower the PTA the better and the closer to 100% the better for AI, but are there any threshholds that have any significance?
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    15 15 20 30 30 55 75 90 NR ​KS7
    10 10 20 15 25 35 65 85 95 WRS 100/92@45/40

  2. #2
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    Is it Articulation Index. There's a Mead Killion article with a full explanation of AII out there, something to do with Cocktail Parties iirc.
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  3. #3
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    Yes, I meant articulation index, although I see where both have been used. Is this the article? https://www.etymotic.com/media/publi...-0047-2002.pdf
    Thanks. Very interesting.
    .25 .5 1 1.5 2 3.0 4.0 6.0 8.0

    15 15 20 30 30 55 75 90 NR ​KS7
    10 10 20 15 25 35 65 85 95 WRS 100/92@45/40

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    Quote Originally Posted by MDB View Post
    Yes, I meant articulation index, although I see where both have been used. Is this the article? https://www.etymotic.com/media/publi...-0047-2002.pdf
    Thanks. Very interesting.
    Yes that's one of them, there's another couple of papers which cover the practical application of it too.
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    Here's something more recent and simpler. https://www.etymotic.com/media/publi...-0113-2010.pdf
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    15 15 20 30 30 55 75 90 NR ​KS7
    10 10 20 15 25 35 65 85 95 WRS 100/92@45/40

  6. #6

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    This is fascinating! I haven't read the longer article, admittedly, just the interview. Interesting about the effect of limiting bandwidth, too, like with Bluetooth.
    250 500 1K 1.5K 2K 3K 4K 6K 8K Costco KS7
    R 25 50 60 60 60 50 50 50 65 SRT: 55dB WRS: 84% @85dB
    L 30 60 60 60 60 55 60 60 70 SRT: 60dB WRS: 88% @90dB

  7. #7
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    Quote Originally Posted by corona View Post
    This is fascinating! I haven't read the longer article, admittedly, just the interview. Interesting about the effect of limiting bandwidth, too, like with Bluetooth.
    Can you see why when manufacturers claim the relevance of over 10Khz bandwidths as a major advance, it's a bit of an irrelevance.

    Good Hi-Fi doesn't necessarily equate with good speech fidelity.
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    Quote Originally Posted by Um bongo View Post
    Can you see why when manufacturers claim the relevance of over 10Khz bandwidths as a major advance, it's a bit of an irrelevance. Good Hi-Fi doesn't necessarily equate with good speech fidelity.
    Oh definitely, but I also note that they say they're giving more importance to the frequencies between 6K and 8K. But over 10KHz -- I know this is an unpopular perspective around here, but I think most of that is marketing. (I note in passing that a long time ago I worked in (analog!) HF radio communications, where speech audibility in the presence of tons of noise and major bandwidth constraints is the big issue, so I'm probably biased from that. And from my own hearing-loss experience, where it's clear that anything over 10K is more bug than feature.) [Edit] I forgot the (not-so-) smiley:
    Last edited by corona; 12-13-2016 at 03:31 PM.
    250 500 1K 1.5K 2K 3K 4K 6K 8K Costco KS7
    R 25 50 60 60 60 50 50 50 65 SRT: 55dB WRS: 84% @85dB
    L 30 60 60 60 60 55 60 60 70 SRT: 60dB WRS: 88% @90dB

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